Measurement of the quantum of thermal conductance
Measurement of the quantum of thermal conductance
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DOI：
10.1038/35010065
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发表时间：
2000-04-27
期刊：
影响因子：
64.8
通讯作者：
Roukes, ML
中科院分区：
文献类型：
--
作者：
Schwab, K;Henriksen, EA;Roukes, ML
介观电子系统物理学的探索已超过 15 年。当载流子的波长或相干长度与样本尺寸相当或更大时，传输过程中就会出现介观现象。该领域的一个引人注目的结果是电传导的量子化，这是在二维电子气库之间形成的准一维收缩中观察到的(1,2)。该系统的电导由收缩内参与的量子态或“通道”的数量决定；在理想情况下，每个自旋简并通道对电导贡献 2e(2)/h 的量化单位。据推测，介观声子系统中的热传输(3,4) 应该可以观察到类似的行为。但到目前为止，在这种情况下尝试的实验尚未产生结论性的结果(5-9)。在这里，我们报告了在极低温度下悬浮绝缘纳米结构中热导 G(th) 的量化极限值的观察结果。我们观察到的行为与弹道一维通道中声子传输的预测 (10,11) 一致：在低温下，Gth 接近最大值 g(0) = pi(2)k(B)(2) T=3h，即热导的通用量子。
The physics of mesoscopic electronic systems has been explored for more than 15 years. Mesoscopic phenomena in transport processes occur when the wavelength or the coherence length of the carriers becomes comparable to, or larger than, the sample dimensions. One striking result in this domain is the quantization of electrical conduction, observed in a quasi-one-dimensional constriction formed between reservoirs of two-dimensional electron gas(1,2). The conductance of this system is determined by the number of participating quantum states or 'channels' within the constriction; in the ideal case, each spin-degenerate channel contributes a quantized unit of 2e(2)/h to the electrical conductance. It has been speculated that similar behaviour should be observable for thermal transport(3,4) in mesoscopic phonon systems. But experiments attempted in this regime have so far yielded inconclusive results(5-9). Here we report the observation of a quantized limiting value for the thermal conductance, G(th), in suspended insulating nanostructures at very low temperatures. The behaviour we observe is consistent with predictions(10,11) for phonon transport in a ballistic, one-dimensional channel: at low temperatures, Gth approaches a maximum value of g(0) = pi(2)k(B)(2) T=3h, the universal quantum of thermal conductance.